Friends and longtime readers are no doubt well away of my fondness for international rankings of all kinds. So it is nice to spice up the usual indexes of social, economic, or political performance and instead compare countries by the interesting new metric of tree wealth.
A team of researchers led by Thomas Crowther of Yale University recently published a study in Nature that looks at where the world’s over 3 trillion trees are located, and how this compares with a country’s geographic size, population, and more.
This might seem like an odd attribute to look at — perhaps suited for nothing more than an amusing fun fact — but as the Washington Post points out, trees are an often vital natural resource well worth studying and preserving.
[Having] lots of trees in a country provides a huge host of benefits — trees are both a natural resource and an asset to humans. They filter water, combat air pollution, sequester huge amounts of carbon that would otherwise reside in the atmosphere, and even, it appears, contribute to human psychological and health benefits. Indeed, large parts of the world population depend on forests for food.
And then, there’s just the emotional connection to nature. “I think people inherently value trees”, said Clara Rowe, a co-author of the study and a recent graduate of the Yale School of Forestry and Environmental Studies, by e-mail. “In the days since our study was published, we’ve heard from individuals all over the world who are concerned about forest resources in their countries.”
Amid widespread environmental degradation and worsening global climate change, such scientific and public interest in the health and abundance of trees is well founded. Where they naturally exist, they are a barometer for the health, vitality, and sustainability of the local ecosystem. So those nations that have managed to preserve as many trees as possible have much to gain, as well as a lot to offer the world at large. Tree wealth is an apt description.
Starting with the most basic measurement, here are the countries with absolute most trees. (The researchers note that these estimates are more accurate with larger countries and less so with smaller ones.)
You can find an interactive version in the Post article, which allows you to select an individual country to see its estimated number of trees.
As one can plainly see, the countries with the most trees in total are, unsurprisingly, the largest ones.
Based on this approach, the world’s overall tree leader is clearly Russia, with 642 billion total trees, followed by Canada with 318 billion and Brazil with 302 billion. The United States is actually fourth overall in this ranking, with 228 billion trees. Other countries with over 100 billion trees include China, with 140 billion and the Democratic Republic of the Congo, with 101 billion. Indonesia comes in 7th, with 81 billion, and Australia 8th, with 77 billion.
Adjusting for territorial size, the next measurement looks at tree density, e.g., the number of trees within a square kilometer (roughly equal to a little over a third of a square mile).
The difference is dramatic: countries with lots of trees in absolute numbers rank low once you adjust for size. Naturally, this applies most strongly to drier countries, such as the desert nations of Saudi Arabia and Qatar, each with just 1 tree per square kilometer.
Relatively large countries like Finland, Sweden, Bolivia, and Indonesia still fare pretty well, as do smaller countries like Gabon, Laos, New Zealand, and Slovenia. As the researchers note in the study:
…in “northern latitudes, limited temperature and moisture lead to the establishment of stress-tolerant coniferous tree species that can reach the highest densities on Earth”. There is more total forest in the tropics, they found, but it isn’t as dense. So the type of forest that a country fosters has a big influence on this metric.
Next up is the number of trees per person. One could imagine that countries with large populations would have a lot less tree wealth to go around, especially with the subsequently high need for space, shelter, and farmland.
[Once] again … vast northern countries like Russia and Canada are surprisingly “tree rich”, with thousands of trees per resident. There are a whopping 8,953 trees per person in Canada. But tropical countries of the southern hemisphere can also hold their own. Here, Bolivia (5,465 trees per person), Gabon (8,131), and the Central African Republic (5,152) also fared quite well.
By contrast, desert countries once again were quite low – Egypt was estimated to have only about one tree per person. The metric is also highly sensitive to population size, meaning that India, with a population of 1.27 billion and a tree population of only about 35 billion, had just 28 trees per person.
Very high tree-to-person numbers were clustered in the northeast of South America: Suriname had 15,279 trees per person, Guyana 14,692, and French Guiana a stunning 20,226. Of course, these countries all have populations under a million people.
So we have gone over the number of trees as they relate to size, density, and population. But what about wealth? Intuitively, fast-growing poorer countries would seem likelier to strip their forests clean, given the greater need for readily available farmland, fuel, and construction material. Most industrialized nations have moved on to other sources, or have the luxury of more efficient (and thus less land-intensive) agriculture; urban parks and tree planting are also a hallmark of greater wealth and development. Various reports and studies seem to bear this out, too.
Let the data do the talking.
Ultimately, the researchers concluded that “it was not clear that there was any meaningful difference overall”.
Rather, it was simply the case that one emerging country grouping, “Middle East, North Africa, Afghanistan and Pakistan” was quite low on trees — but then, that’s not surprising given the prevalence of desert in these countries. So it seems odd to relate this to economics, rather than simple geography. Simply put, some countries, due to their environments and climatic regimes, just can’t host as many trees as others.
“If you said to me, okay, the GDP per capita of Costa Rica is $8,000, I would have no way of telling you how many trees there are in Costa Rica or how dense those trees are”, said Yale’s Clara Rowe. She said that the most meaningful way of looking at the relationship between a country’s wealth and its tree resources would be to calculate a nation’s “forest potential” — how many trees it is actually capable of supporting — and then compare that with how many it actually has, which would then reflect how much the country has exploited those resources, as opposed to preserving them.
“That can really give us a better sense of what percentage of forest can be lost in every single country, and then maybe we can start relating that to things like GDP”, Rowe said. But the researchers haven’t done that analysis on a country-by-country level yet.
Studying “forest potential” would definitely be the next step. Granted, it is important to keep in mind that there is a big difference between having lots of trees and having lots of forest; a country’s cities might have plenty of trees in its parks, medians, and public spaces, but these would not support the sort of thriving ecosystem as an unspoiled forest would. While trees are important in their own right, for reasons specified earlier, they need to be in abundant number and left undisturbed to support certain wildlife. That would be a whole different sort of wealth to look into.